Woosh is a payments app and primitives kit for USDC on Arc Testnet. Five Foundry contracts do the on-chain work: WooshSlugRegistry resolves named payment links, WooshInvoiceRegistry stores tamper-proof invoices whose pay() enforces the exact recorded amount, WooshStrategyRegistry custodies per-strategy budgets for recurring payments, DCA, and weighted portfolio allocations, WooshSavingsVault enforces rule-based auto-sweeps on-chain, and WooshBatchPay settles payroll in one all-or-nothing transaction. Scheduled actions run keylessly — a cron executor drives a Circle Developer-Controlled Wallet through sdk/src/shared/lib/dcw.ts with no raw private key, and swaps route through Synthra SynRoute in src/shared/lib/synroute.ts with actual-output accounting from balance deltas. The whole contract set ships again as a standalone forkable repo, woosh-arc-primitives, with a viem-only TypeScript SDK under sdk/src/entities covering typed reads, id derivation, and allocation math. Arc's 18-versus-6 USDC decimals quirk is handled once at every layer, from NATIVE_PER_ERC20 in WooshSavingsVault.sol to the SDK's whole-unit flooring, and a 72-test Foundry suite backs the contracts.